Imaging Studies Non-DM CAC>100 T1D CAC< 100 T1D CAC> 100 MPI 5 10 10 CMR 5 10 10 InvCBF 5 5-10 5-10 Subject will be recruited to complete all three parts of the protocol myocardial perfusion imaging (MPI); cardiac MR assessment of myocardial blood flow reserve (MBF); and only those subject with significant symptoms or clinical indications proceeding to invasive "Catheterization Laboratory" assessment of CBF reserve (Invasive CBF) Aim 1. Determine the relationship between myocardial perfusion index, regional CBF and invasively measured coronary perfusion reserve The first approach will be to assess the differences in myocardial perfusion between T1D and non-DM subjects employing vasodilatory stress with regadenoson. The myocardial perfusion index as described previously will be calculated for each individual. The relative perfusion index will be directly compared to the invasively obtained CBF reserve in each vascular territory assessed.